The present invention relates to an airbag apparatus having an airbag that is deployed at a side of an occupant of a vehicle when an impact of a force greater than a predetermined value is applied to a side of the vehicle body due to a side collision.
Such side airbag apparatuses have been disclosed in, for example, Japanese Laid-Open Patent Publication No. 2000-177527 (first prior art), Japanese Laid-Open Patent Publication No. 2000-280853 (second prior art), and U.S. Pat. No. 5,112,079 (third prior art).
In the first prior art, as represented by FIG. 34, a side airbag apparatus 542 is mounted in a backrest 541a of a vehicle seat 541 as shown in FIG. 34. The interior of an airbag 543 of the side airbag apparatus 542 is divided by a dividing seam 544 into a first chamber 545 and a second chamber 546. The first chamber 545 inflates at a side of the thorax Pc of an occupant P sitting on the vehicle seat 541. The second chamber 546 inflates at a side of the lumbar region Ph of the occupant P.
The side airbag apparatus 542 has a gas generator 547 for deploying the airbag 543. A pre-chamber 548 is located about the gas generator 547. The pre-chamber 548 is connected to the first chamber 545 through first small holes 549 and to the second chamber 546 through second small holes 550. The total opening area of the first small holes 549 is less than the total opening area of the second small holes 550.
When an impact of a force that is greater than a predetermined value is applied to the side of the vehicle body due to a side collision, the gas generator 547 generates gas, which is first supplied to the pre-chamber 548. The gas is then supplied to the first and second chambers 545, 546 through the first and second small holes 549, 550 of different total opening areas at different flow rates. Due to the difference of the gas flow rates, the first and second chambers 545, 546 are inflated such that the internal pressure of the first chamber 545 is lower than the internal pressure of the second chamber 546.
In the second prior art, as represented by FIG. 35, also, a side airbag apparatus 642 is mounted in a backrest 641a of a vehicle seat 641 as shown in FIG. 35. The interior of an airbag 643 of the side airbag apparatus 642 is divided into a first deployment region 652 and a second deployment region 653 by a substantially vertical dividing wall 651. The first deployment region 652 inflates at a position that is at rear of an arm Pa of the occupant P. The second deployment region 653 inflates to contact the arm Pa. During a side collision, a gas generator 647 generates gas, which immediately inflates the first deployment region 652 from the lower part to the upper part. After a delay, the second deployment region 653 is inflated from the lower part to the upper part.
The third prior art discloses a side airbag apparatus having a large airbag. This airbag is deployed to cover a large area including the head and the lumbar region of an occupant.
In the first prior art, the first chamber 545, which corresponds to the thorax Pc of the occupant P is inflated with a pressure that is lower than that of the second chamber 546, which corresponds to the lumbar region Ph. Therefore, the thorax Pc, which is relatively vulnerable to impacts, is more softly received compared to the lumbar region Ph. Therefore, the impact of a side collision is not greatly applied to the thorax. However, since the internal pressure of the first chamber 545 corresponding to the thorax Pc is relatively low, if the body side portion of the vehicle is greatly deformed inward of the passenger compartment due to a side collision, the thorax Pc might not be sufficiently protected.
In the second prior art, the vertically extending first and second deployment regions 652, 653 are inflated substantially with the same pressure. Therefore, the part of the body of the occupant P from a shoulder Ps to the lumbar region Ph is uniformly contacts the inflated airbag 643. Therefore, like the first prior art, the thorax Pc might not be sufficiently protected.
The third prior art discloses the largely deployable airbag that simply protects the body of an occupant over a large area, but does not disclose any deployment modes of the airbag to correspond to specific parts of the occupant's body. Therefore, the third prior art is not expected to effectively protect occupants by taking the characteristics of a human body into consideration.